[paper] Perspective of Ultra-Scaled CMOS

Ab initio perspective of ultra-scaled CMOS

from 2D-material fundamentals to dynamically doped transistors

Aryan Afzalian 

Open Access; npj 2D Mater Appl 5, 5 (2021) 

DOI: 10.1038/s41699-020-00181-1 

Abstract: Using accurate dissipative DFT-NEGF atomistic-simulation techniques within the Wannier-Function formalism, we give a fresh look at the possibility of sub-10-nm scaling for high-performance complementary metal oxide semiconductor (CMOS) applications. We show that a combination of good electrostatic control together with high mobility is paramount to meet the stringent roadmap targets. Such requirements typically play against each other at sub-10-nm gate length for MOS transistors made of conventional semiconductor materials like Si, Ge, or III–V and dimensional scaling is expected to end ~12 nm gate-length (pitch of 40 nm). We demonstrate that using alternative 2D channel materials, such as the less-explored HfS2 or ZrS2, high-drive current down to ~6 nm is, however, achievable. We also propose a dynamically doped field-effect transistor concept, that scales better than its MOSFET counterpart. Used in combination with a high-mobility material such as HfS2, it allows for keeping the stringent high-performance CMOS on current and competitive energy-delay performance, when scaling down to virtually 0 nm gate length using a single-gate architecture and an ultra-compact design (pitch of 22 nm). The dynamically doped field-effect transistor further addresses the grand-challenge of doping in ultra-scaled devices and 2D materials in particular.

Fig: Switching energy vs delay (EDP) of high-performance MOSFET and D2-FET inverters. EDP of 1ML-HfS2 high-performance inverter cells, at various VDD (0.4 V to 0.7 V), made of L = 5 nm and L = 3 nm stacked DG MOSFETs (5 ribbons/device) and L = 0 nm and L = nm stacked SG-D2-FETs (nine ribbons/device). The EDP performance of Si HP inverter cells made of L = 12 nm stacked Si-GAA MOSFETs (tS = 5 nm, 8 wires/device) and L = 5 nm stacked Si SG-D2-FETs (tS = 3 nm, 7 ribbons/device) are also shown for comparison. The inverters are loaded with a 50 contacted-gate-pitch-long metal line (https://irds.ieee.org/editions/2018). The extrinsic capacitances of the cell layout are also included in the load capacitance. IOFF = 10 nA/μm. ΔL = 4 nm for the D2-FETs.

Acknowledgements: Part of the computing resources and services used in this work were provided by the VSC (Flemish Supercomputer Center), funded by the Research Foundation–Flanders (FWO) and the Flemish Government. The author acknowledges the support of Dr. G. Gaddemane for the DFTP e-ph coupling calculations.

Open Access: This article is licensed under a Creative Commons Attribution 4.0 International License